1. Technical Field
The present invention relates to a sensor unit and a motion detection device.
2. Related Art
In recent years, a device for analyzing a motion of a test object (a human) has been demanded in a variety of fields.
By analyzing the motion form of the test object (an athlete) such as a trajectory of a swing of sports equipment such as a golf club, tennis racket, or a baseball bat to thereby select the sports equipment suitable for the test object and improve the motion form based on the analysis result, improvement in athletic ability can be achieved.
As such an analysis device and an analysis method of the motion, for example, JP-A-2010-110382 discloses a motion detection device using an optical motion capture device and an analysis method. The device is for shooting a measurement target object (a test object and sports equipment) attached with a marker using an infrared camera or the like, and then calculating the movement trajectory of the marker using the image thus shot to thereby analyze the motion.
Further, as the analysis device and the analysis method of a motion, for example, JP-A-2008-73210 discloses a motion detection device and an analysis method for detecting the motion of the test object due to a swing of sports equipment using an inertia sensor attached to the test object, and then analyzing the motion based on the motion data of the test object output from the inertia sensor. Such a device does not require a motion capture device such as an infrared camera, and therefore, has an advantage that handling is simple and easy.
Here, when detecting the motion of the test object using an angular velocity sensor or the like as the inertia sensor and then analyzing the motion, it is required to remove a bias of the inertia sensor. In other words, it is required to determine an origin of the motion of the test object.
The bias is a collective term including a zero bias occurring in the initial state prior to the start of the motion of the test object and in which the angular velocity is zero, and a drift due to an external factor such as a power supply fluctuation or a temperature fluctuation.
In order to remove the bias, it is required to obtain a bias value in the initial state. For example, in the swing analysis of a golf club, a rest period in which the test object stops is set before starting the swing. Then, the bias value in the initial state is determined based on a signal output from the angular velocity sensor or the like in the rest period. In other words, the origin of the motion of the test object is determined.
However, since the motion (swing) is started after visually checking a display device of the analysis device in order to confirm that the bias value and the origin of the motion are determined, there is a possibility that the appropriate swing analysis cannot be achieved due to the deviation of the visual line of the test object. Further, in the case of adopting a method in which other people than the test object checks the display device and the motion (swing) is started in response to a sign such as a voice, since other people than the test object are involved, there is a problem of lacking convenience of the motion analysis.